Method of finishing a slide fastener chain

Abstract

A method is disclosed whereby a pair of stringers for slide fasteners are subjected to heat treatment to permit the fibers of stringer tapes to be contracted particularly in the region of longitudinal edge portions of the tapes where rows of fastener elements are secured. The thus contracted tape edges are further shaped by compression molding so as to present a transverse cross section complimentary with that of a guide channel in a slider.

What is claimed is: 
     
       1. In the manufacture of a slide fastener chain having a pair of stringer tapes coupled together and a row of filamentary coupling elements having a succession of loops and secured by a binding thread system to a longitudinal edge of each of said tapes, said binding thread system partly covering at least one of upper and lower surfaces of said loops of the coupling element row, the method which comprises the steps of: (a) transporting said fastener chain unidirectionally at a constant rate of speed;   (b) passing said chain through a first treatment zone where said chain is thermally preset at a temperature to permit the fibers of said stringer tapes and said binding thread system to become thermally contracted;   (c) subsequently introducing said chain into a second treatment zone where said binding thread system of said chain is thermally compressed at a temperature similar to that in said first treatment zone, whereby said binding thread is plastically deformed to assume a transverse cross section substantially identical with that of a slider guide channel; and   (d) cooling said chain to set it, said rows of coupling elements being coupled together prior to, and remaining coupled together during, the passing of said chain through said first and second treatment zones.   
     
     
       2. The method as claimed in claim 1, in which said stringer tapes are formed of polyester yarn and the temperature in said first and second treatment zones is about 200° C. 
     
     
       3. The method as claimed in claim 1, in which said stringer tapes are formed of nylon yarn and the temperature in said first and second treatment zones is about 130° C. 
     
     
       4. The method as claimed in any of claims 2, 3 and 1, in which a core cord extends through said loops of said coupling element row and in which said binding thread system comprises a first group of binding warp threads partly covering upper surfaces of said loops of the coupling element row, a second group of binding warp yarns partly covering lower surfaces of said loops of the coupling element row, relatively large diameter thermoplastic binding yarns extending along heel portions of said loops of said coupling element row, and a binding weft-thread binding together said core cord, binding warp threads and thermoplastic binding yarns, said thermoplastic binding yarns being plastically deformed by said thermal compression in said second treatment zone to conform to a slider guide channel and with portions penetrating between heel portions of successive ones of said loops.